Process of manufacturing benzoate.



UNI ED sTATEs PATENT oFFIoE.

EDWIN 0. BARSTOW, or MIDLAND, MICHEGAN, .AS'SIGNOR TO THE now CHE ICALCOMPANY, OF MIDLAND, MICHIGAN, A CORPORATION or MICHIGAN.-

rnoonss or MANurAo'rimINe BENZOATE.

No Drawing.

Specification of Letters Patent. Y Patented Nov. 9, 1909, Applicationfiled October 25,1905. Se1-ia1No.284,402.

To all whom it may concern: I

Be it known that I', EDWIN O. BARS'IOW, a citizen of .the'United States,resident of Midland, county of Midland, and State of Michigamhaveinventeda new and useful Improvement in Processes vof ManufacturingBenzoates,.of which the following is a specification, the principle ofthe invention bein herein explained and the best mode in whic I- havecontemplated applying that.

rincip'le, so as to distinguish it from other inventions. p

' M invention relates to processes of making 'enzoic acid and benzoatesand particu larly to the manufacture of calcium benzoate;

'Said 'in'vention consists of 'ste s hereinafter fully described andspeci cally set forth in the claims. j

The following' 'description. sets forth in detailcertain steps embodyingmyinvention', such disclosed steps constituting but-one of various waysin-which the principle of the invention may be used.

Some of the" various methods by which benz'oic and benzoates haveheretofore been manufactured are as follows: (1) 'from gum' benzoin andother natural gums by sublimation or extraction, such-processes in-fvolvihg the treatment of the gum simply with heat, or with an alkalinesolution to dissolve the benzoic acid,-and the subsequent precipitationby means of a mineral acid; (2) from urine and hi puric acid b wellknown processes; (3) om benzyl c lorid, benzal chlorid orbenzotri-chlorid, by the following processes: (a) from benzyl chloridbyoxidation withhot dilute nitric acid, givingas resultant productsbenzoic acid and hydrochloric acid; (b)from benzal chlorid as. aby-product in the manufacture of benzaldehyde, the benzal chlorid beingtreated withasolution of lime; (c) from ben'zo-triichloridby heatingwith water .un'derpres sure, with lime and water or a solution ofcaustic soda and whiting.

My invention relatesto-those of the above- .mentioned methods in whichbenzoic acid or the benzoates are manufactured from homologuesof benzenecontaining one side chain, and particularly to that method in whichcalcium benzoateis manufactured from benzyl chlorid, although the broadspirit. ofmy invention comprehends the manufacture of. benzoates from'benzal chlorid; also from products of toluene and calicum benzoa-t'e,as

acid or benzoates. When manufactured-flay chlorid, the old process issubject to the difficulty that the resultant product always contain'simpure acids in the form of chlorbenzoic acids. I

product ofone of the homolognesl ofben- ,zene, such product having onlyone side chain,"and"then I oxidize such product to benzoic acid or ahenzoate by means of a compound containin chlorin. Hou' e\ 'e,r, ,lj

would consist of only one step, v1z., the oxidation of such product bythe chlorincontaining compound.

In order to typify the methods by which my process may be effected Ishall describe that derivative of toluene whichf'has bne by means ofbleaching powder, and lime. It will be understood, however, that othering from the spiritflof my invention.

When toluene ,is chlorinated to the first stage, either benzyl chl'orid.Jr a chlortoluene is formed and the tendency is for each molecule ofthe toluene to take one atom of the chlorin before any molecule takes asecond atom, this atom of chlorin going into the-side chain or methylradical of the toluene in a great majority of cases,

benzyl alcohol, benz-aldehyde, and other products. intermediate of thechlorination is particularly pointed out and claimed in mycopendingapplication for U. S. Letters In the carrying out of myiinproyed, process I produce a chlorin substitution the same as carriedout when manufacture V which is unsatisfactory when the main pnrposesought is the manufacture of bCllZOlC the old method noted above frombenzo-trimay start with the clilorin substitutionprod; not and in thatcase my improved process.

atomof chlorin in one. side chain, '\"i z..,' benzyl "chlor1d,..andthenoxid ze/the same ioif compounds may be utilized withoutdepartchlorin, whatever it I took up two atoms if the conditions underwhich the -chlorination takes place are proper, such conditions beingprincipally that the chlorination be aided by heat and take place in thesun light. If the chlorination is and dark, or there be present anycarrier .such as iodin or ferric chlorid, the chlorin the part stillremaining as a liquid. When the chlorin atom that is taken up goes intothe side chain, it forms benzyl chlorid, and when it goes into the ring,as it does in a comparatively few cases, it forms a chlortoluene. Thischlor-toluene will not form a benzoic acid when treated according to myprocess, so that it will not form an impurity in my resultant product, Itherefore obtain a benzoate which holds very little ring does hold beingobtained from those few molecules of toluene which of chlorin, of whichtwo atoms one went into the rin and one into the side chain; because, itboth of the chlorin atoms or all three of them, if some molecules oftoluene had taken up three atoms, had gone into the ring, theyv wouldnot form a benzoic acid at all, or, if they had gone into the sidechain, the would have formed a benzoi c acid containing no ring chlorin.4O

It will be understood, therefore, that if I pass into the toluene onlysuch a quantity of chlorin as is necessary to furnish each molecule withone atom, toluene will be chlorinated to the first in the mannerdescribed above, and 'by far the greater part of-it will be in the formof benzyl chlorid, the remaining smaller part being in the formof'chlor-toluene, which latter is inert, when I oxidize, ashereinafterfully described, and, consequently does not form a chlor-benzoic acidwhich would be an impurity in the resultant product. It will be seen,therefore, that if I should chlorinate the toluene to the second orthird stage, the probabilities would be greatly increased of obtaininga. product in which chlorin had entered both the ring and the side chainof the toluene, and thus result, when the oxidation is effected, in theproduction of a chlor-benzoic acid, as noted above. Another objection tothe chlorination of the toluene to the secondstage, viz: tobenzalchlorid or to the third stage, viz: to benzo-tri-chlorid, is thatmuch stage efiected in the coldsubstantially all of such more aptoluenewith paratus is required to treat. a given amount sary to have oftoluene in a given time, which is uneconomical since the chlorination oftoluene is atthe best. a delicate and comparatively expensive operation.Furthermore, the rate of absorption of the chlorin is much faster duringthe first stage of the chlorination than it is during the later stages;also, the loss due to decomposition is not nearly so great when benzylchlorid is formed as it is when benzotri-chlorid is formed, due to thefact that the liquid remains in the apparatus less than one-third aslong, "and also to the fact that under the conditions benzo -tri-chlorid decomposes more readily than benzyl chlorid. My improvedprocess, then consists in chlorinating toluene to the first stage, viz.to benzyl chlorid and then heating the latter with a solution ofbleachin powder and lime, calcium benzoate thus icing formed, whichcrystallizes out upon cooling the solution. Sodium benzoate may beobtained by adding a solution of sodium carbonate to a hot solution ofcalcium benzoate. If the chlorination hasreached the second stage,calciuin'benzoate may be obtained from the benzal chlorid by heating thelatter with a solution of bleaching powder and lime.

As a guide in practically making out my process, the following data,illustrating the relative quantities and course of procedure wherethe-specific materials named are employed, is furnished. One part ofbenzyl chlorid is agitated with three parts of water to form an emulsionand then is run into a solution made by dissolving three and one-halfparts of bleach in twenty parts of water and thereupon adding one-thirdpart of slaked lime. Upon heating and stirring this mixture in asuitable apparatus calcium benzoate isformed according to the followingreaction The apparatus preferably employed consists of a commoncement-lined iron retort provided with a reflux condenser, an agitator,and direct steam and water connections for regulating the temperature.The. preferred temperature is about 95 C.

Bleaching powder or chlorid of lime is made by absorbing chlorin inslaked lime andthe oxidizingconstituent of bleaching powder may beregarded as having the formula CaOCh. However, the latter may beregarded as a -'mixture in equal molecular proportions of, calciumchlorid and calcium hypochlorite, thus:

and in this case the calcium hypochlorite would be regarded as theactive oxidizing constituent. In oxidizing a derivative of bleachingpowder it is neceslime present in order to neutralize the benzolc orhydrochloric acid as soon as formed and. thus keep the solution alwaysalkaline. Otherwise, if the solution is allowed, to become acid thebleaching powder is \decomposed with liberation of free chlorin andconversion of the hypochlorite into chlorate and chlorid. Since ordinarybleaching powder always contains a considerable amount of caustic lime,it is possible to efi ct the oxidation of the benzylor alkaline earthhydrates either in solution plete conversion to benzo-tri-chlorid, suchor in the solid state. As an example of the foregoing. sodiumhypochlorite is obtained, which is an active oxidizing agent, whenchlorin is absorbed in a. solution of sodium hydrate, thus:

QNaOH-t-Ch:NaClQt-NaOCl-t-HQ.

This method, in which alkaline hypochlorites are utilized as theoxidizing agents, is

particularly pointed out and claimed in an.-

other co-pending application for U; S. Letters Patent, Serial No.305,958, filed March- I prefer to use lime as the reagent. with which toneutralize'the acid formed, but it is not, necessary to do so, since Ican use the hydrate of any alkaline or alkaline earth metal.Furthermore, I prefer to use toluene as the source of benzoic acid, but

any of the homologues of benzene contain .ing one side chain wlll servethe purpose.

The gist of my invention, then, consists in the oxidation of thederivatives of members of the benzene series of hydrocarbons by means ofbleaching powder, or similar hypochlorite containin g substances, suchderiva tives, as benzyl chlorid, benzal chlorid, benzaldehyde, benzylalcohol or any of the side chain deriyatives .of the homologues ofbenzene which require oxidation to form benzoic acid, being obtained inany desirable way.

It wlll be noted that while I prefer to stop the chlorination of thetoluene at the first stage, viz., at the formation of benzyl chlorid, itis not necessary to do so, but that I can stop'at any point short of thecomchlorinated toluene then being in the form of a mixture of toluene,benzyl chlorid, benzal chlorid, benzo-tricl1lorid, and small amounts ofdecomposition products and compounds. with chlorin in the ring, thismixture, upon being treated with a solution of bleaching powder andlime, being oxidized. directly .to calcium benzoate without furtherchlorination, which further-chlori-' nation would give aprotlnctyielding a less pure calcium benzoate." I prefer totrea-t' thechlorinated toluene. directly with liine and bleaching powder, butImight convert 'the chlorids of toluene into intermediate products; andthen oxidize'the lattertobenzoates, for instance, converting benzylchlorid into benzyl alcohol by heating with a solution of sodiumcarbonate or by any other suitable method, and converting benzal chloridinto benz-aldehydewith'a limesolution, and then oxidizing thebenz-aldehyde into benzoic acid'by means of bleaching powder. any:oxidation to form benzoic acid and hence my process is not 'applicabl'ethereto.

'By my improved processl obt-ain' a pure benzoic acid, due to thesm-allpercentage of chlorinated toluene which contains it's chlorin both inthe side chain and in the ring; furthermore, in order toiobtain a givenamount of benzoates, require less than onethird of the apparatus andonly one'third of the amount of chlorin gas t-liatfhasbeen necessaryheretofore when the toluene was Ben'zo-trichlorid does not requireconverted into benzo-tri-chlorid, the remain- 'n oxidationfbeingeffected means of ,hIorid of lime which is easily. and cheaply made byabsorbing chlorin in 'slaked lime.

' It has been stated that the class of compounds which my improved",process is ada ted to utilize as a starting point for the oxi ationstep,that constitutes the process proper, is merely exemplified in the.benzyl chloridl The members of the general class of compounds available-for use in the process may be appropriately denominated,sidechain-substitution products of afme'mber of the benzene seriesofhydrocarbons, where by such term I mean hydrocarbon derivatives inwhich one or more hydrogens of a side-chain have been replaced eitherdirectly or indlrectly by chlorin, oxygen, hydroxyl,

or similar elements or radicals. Thus in its I specific aspects thepresent application deals with a side-chain substitution roduct in whichchlorin figures as the substituting element; While in the companionapplication,

Serial No. 305,959, referred to abo 'e, a

product in which the hydrogen is. similarly replaced by hydroxyl isemployed. The sub-.

type of product-{exemplified .in the .latter case, While included in thegeneric term above defined-{has for the purpose of such companion aplication been called a partially oxidize oxygen-containing product of amember ofthe benzene series of hydrocarbons.

"Having described my invention in detail, that which I particularlypoint out and distinctly claim is:

1. In a process v of manufacturing 1 beni zoates, the step which of amember .to the acid a side-chain substitution product zoates, the stepcarbons, by means of bleaching powder in consists in oxidizing lo theacid a side-chain substitution .product of a member of the benzeneseries of hydrocarbons, by means of a chlorin-containing reagent in thepresence of a basic neutralizing reagent and a suitable solvent.

2. In a process of manufacturing benzoates, the step which consists inoxidizing to the acid a SldG-Clmlll substitution product of the benzeneseries of hydrocarbons, by means of a chlorin-containing reagent in thepresence of an alkaline earth hydrate and a suitable solvent.

3. In a process of manufacturing benzoates, the ste which consists inoxidizing of a member of the benzene series of hydrocarbons, by means ofa ehlorin-containing reagent in the presence of lime and water.

In a process of manufacturing benwhich consists in oxidizing to the acida side-chain substitution product of a member of the benzene series ofhydrothe presence of a suitable solvent, such bleaching powdercontaining sufiicient lime to neutralize the acid formed by the reac-.tion.

In a process of manufacturing benzoates, the step which consists inoxidizing to the acid a side-chain substitution product of a member ofthe benzene series of hydrocarbons, by means of bleaching powder in thepresence of water and of lime in excess of that contained in saidbleaching powder.

6. Ina process of manufacturing ben-- zoates,- the step which consistsin oxidizing to the acid a chlorinated derivative of a memberof thebenzene series of hydrocarbons, by means of a chlorin-containing reagentin the presence of a basic neutralizing reagent and a suitable solvent.

7.- In .a process of manufacturing benbons, by

zoates, the step which consists in oxidizing to the acid achlorinatedderivative of 'a' member of the benzene series of hydrocarbons, by meansofa chlorin-containing reagent in the presence of an alkaline earthhydrate and a suitable solvent- 8. In a process of manufacturingbenzoates, the step which consists in oxldizing to the acid achlorinated derivative of a member of the benzene series ofhydrocarbons, by means of a chlorin-containing reagent in thepresence-of lime and water.

9. In a process of manufacturing beni zoates, the step which consists inoxidizing to the acid a chlorinated derivative of a member of thebenzene series of hydrocarmeans of bleaching powder in the presence of asuitable solvent, such bleachpowder containing sufficient lime toneutralize the acid formed by the reaction.

10. In a process of manufacturing benzoates, the step which consists inoxidizing to the acid a chlorinated derivative of a member of thebenzene series of hydrocarbons, by means of bleaching powder in thepresence of water and of lime in excess of that contained in saidbleaching powder.

11. In a process of manufacturing ben- =zoates, the step which consistsin oxidizing benzyl chlorid to 'the acid by means of a chlorin-containinreagent in the presence of a basic neutraIizing reagent and a suitablesolvent.

12. In a process of manufacturing benzoates, the step which consists inoxidizing benzyl chlorid to the acid by means of a chlorin-containingreagent in the presence of an alkaline earth hydrate and a suitablesolvent.

13. In a process of manufacturing benzoates, the step which consists inoxidizing benzyl chlorid to the acid by means of a chlorin-containingreagent in the presence of I lime and water.

14. In a process of manufacturing benzoates, the step which consists inoxidizin benzyl chlorid to the acid by means of bleaching powder in thepresence of a suitable solvent, such bleaching powder containingsuiiicient lime to neutralize the acid formed by the reaction.

15. In a. process of manufacturing benzoates, the step which consistsinoxidizing benzyl chlorid to the acid by means of bleaching powder inthe presence of waterand lime in excess of that contained in saidbleaching powder.

16. The process of manufacturing benzoates, which consists in forming anemulsion of benzyl chlorid with water, mixing such emulsion with asolution of bleaching powder and water to which has been added aquantity of slaked lime, and thereupon heating.

Signed by me this 17 day of Oct. 1905.

' EDIVIN O. BAR-STOW.

Attested by- 'Inos. GnIswoLD, J12, CARL IV. BENNETT.

